1. Field of the Invention
The present invention relates to a power adapter and more particularly, to such a power adapter that has an air passage and at least one exhaust port for causing circulation of cooling air to carry heat away from the internal electronic component parts during operation.
2. Description of the Related Art
Advanced power adapters are small-sized. Therefore, the heat dissipation arrangement in an advanced power adapter is quite important. FIG. 1 is a schematic sectional plain view of a conventional power adapter. According to this design, the power adapter comprises a housing 80, a printed circuit board 81, a plurality of electronic component parts 82, a heat sink 83, and an electric fan 84. The housing 80 has a plurality of air vents (not shown). The heat sink 83 absorbs heat from the electronic component parts 82. The fan 84 causes currents of air to carry heat from the heat sink 83 to the outside open air through the air vents of the housing 80 so as to lower the inside temperature of the power adapter.
According to the aforesaid prior art design, the power adapter uses an electric fan to cause currents of air for lowering the inside temperature. However, the use of the electric fan greatly increases the cost. Further, during the operation of the power adapter, the electric fan causes noises.
Therefore, it is desirable to provide a power adapter that eliminates the aforesaid drawbacks.